data science cs109 homework1

1.python及其第三方庫的引入

python和pip的安裝會出現各種錯誤，在安裝python之前一定要安裝openssl、openssl-devel、libxml，libxml-devel,然後才能以此安裝setuptools和pip，pip是python的管理器，能夠自動下載安裝很多python第三方包，非常方便。
小編搗鼓了好幾天，事實證明，python3還不是很成熟，第三方包非常難安裝，一直會出錯，最好還是使用python2.7來學習機器學習
data science的老師在homework中給出了詳細的需要下載的第三方庫的列表：

#IPython is what you are using now to run the notebook
import IPython
print "IPython version:      %6.6s (need at least 1.0)" % IPython.__version__

# Numpy is a library for working with Arrays
import numpy as np
print "Numpy version:        %6.6s (need at least 1.7.1)" % np.__version__

# SciPy implements many different numerical algorithms
import scipy as sp
print "SciPy version:        %6.6s (need at least 0.12.0)" % sp.__version__

# Pandas makes working with data tables easier
import pandas as pd
print "Pandas version:       %6.6s (need at least 0.11.0)" % pd.__version__

# Module for plotting
import matplotlib
print "Mapltolib version:    %6.6s (need at least 1.2.1)" % matplotlib.__version__

# SciKit Learn implements several Machine Learning algorithms
import sklearn
print "Scikit-Learn version: %6.6s (need at least 0.13.1)" % sklearn.__version__

# Requests is a library for getting data from the Web
import requests
print "requests version:     %6.6s (need at least 1.2.3)" % requests.__version__

# Networkx is a library for working with networks
import networkx as nx
print "NetworkX version:     %6.6s (need at least 1.7)" % nx.__version__

#BeautifulSoup is a library to parse HTML and XML documents
import BeautifulSoup
print "BeautifulSoup version:%6.6s (need at least 3.2)" % BeautifulSoup.__version__

#MrJob is a library to run map reduce jobs on Amazon's computers
import mrjob
print "Mr Job version:       %6.6s (need at least 0.4)" % mrjob.__version__

#Pattern has lots of tools for working with data from the internet
import pattern
print "Pattern version:      %6.6s (need at least 2.6)" % pattern.__version__

(1)這裏面matplotlib安裝出現了很多問題，其中matplotlib安裝必須依賴freetype、pnglib，還有yum install gcc-c++
(2)pandas安裝需要依賴 yum install cython，安裝起來會死機，還不知道爲什麼
（3）beautiful4就是bs4啊啊
（4）pattern安裝時候報錯，問題出在setup.py中的print是Python2.x版本的，而python是3.x版本的，需要將setup.py文件中所有的print換爲print();

此上是我總結的血淚史，感覺錯誤的關鍵是版本的不匹配，由於我對linux不是很熟悉，所以只能慢慢摸索了，好在在自己的電腦上成功的安裝了所有的第三方包，實驗室的還有其他奇葩的錯誤，再接再厲，那麼下面開始簡單的代碼吧。

2.代碼例子

#this line prepares IPython for working with matplotlib
%matplotlib inline  

# this actually imports matplotlib
import matplotlib.pyplot as plt  

x = np.linspace(0, 10, 30)  #array of 30 points from 0 to 10
y = np.sin(x)
z = y + np.random.normal(size=30) * .2
plt.plot(x, y, 'ro-', label='A sine wave')
plt.plot(x, z, 'b-', label='Noisy sine')
plt.legend(loc = 'lower right')
plt.xlabel("X axis")
plt.ylabel("Y axis")  

問題：
（1）No module named _tkinter
解決方案：
安裝tck-devel、tk-devel，重新編譯python
（2）no display name and no $DISPLAY environment variable
解決方案：
在文件頭添加implotlib.use()
或者import matplotlib >>> matplotlib.matplotlib_fname() # This is the file location in Ubuntu ‘/etc/matplotlibrc’
找到matplotlibrc之後，將backend從tkAGG修改爲AGG
上面的方法會導致show函數不能顯示圖像，解決的根本方法還不知道，但是後續會繼續尋找方法
（3）libpng16.so.16: cannot open shared object file: No such file or directory
[root@root python]
解決方案：